Water quality meter and water quality monitoring system

ABSTRACT

A water quality meter is composed of a plurality of water quality monitoring meters including analyzing units for analyzing water samples introduced from a water distribution pipe, each analyzing unit analyzing the water samples and a measuring cell, and a liquid introducing unit integrated with the analyzing units, which is composed of a single member in which a plurality of fluid flow paths for feeding various types of liquid including the water sample into the analyzing unit are formed. Furthermore, the cells and the plurality of three-dimensional fluid flow paths formed in the single member are fabricated by a micro-fabrication technique using photo-curing resin.

This is a division of U.S. patent application Ser. No. 09/281,098, filedMar. 29, 1999, now U.S. Pat. No. 6,290,908.

BACKGROUND OF THE INVENTION

The present invention relates to a water quality meter to measure thequality of drinking water distributed via pipes and a water qualitymonitoring system using the water quality meter.

As an example of a water quality monitoring system, an automatic waterquality measurement system known to be used in Tokyo, and its designspecification is described in a paper of The Journal of The Society ofInstrument and Control Engineers (Japan), Vol. 33, No. 8, August 1994,pp. 649653.

In this water quality measurement system, a water quality meter isprovided at each of the piping subsystems composing a water supplypiping network at a water supplier, and it continuously measures thewater quality of each piping system. Furthermore, the measured waterquality is transmitted to a control center with a telemeter at regularintervals.

As a means for measuring the water quality for end users, a manualanalysis in which the distributed water of the end user is sampled andmanually analyzed with a reagent or an off-line measurement using aportable water quality meter is performed.

In a conventional water quality monitoring system such as theabove-mentioned system, since a water quality meter is provided in eachwater piping subsystem, the number of the provided meters iscomparatively small, and the average quality of water distributed ineach subsystem can be determined. However, the conventional system has aproblem in that the quality of water which end users drink is notdetermined.

The quality of water is measured and controlled at a water supplyingfacility. However, the water quality is degraded while water passesthrough a water distribution piping network. For example, theconcentration of chlorine to maintain the bactericidal activity indrinking water is decreased due to chemical reactions with the materialscomposing the water distribution system or with components contained inthe drinking water. Also, the chromaticity of drinking water isincreased by coloring due to stains on the inside surfaces of the pipes,and the turbidity of drinking water is also increased due to the peelingof deposits on the inside surfaces of the pipes. Although theabove-mentioned degradation of water quality is naturally caused in mainpipes, this degradation is more strongly caused in end side pipes in awater distribution piping network or in pipes in the houses of endusers. It is well known that the concentration decrease of residualchlorine in water is proportional to the staying time in water. Thestaying time of chlorine in water is longer in the end side pipes thanin the main pipes in which water always flows. Therefore, theconcentration of residual chlorine is decreased in the end side pipes.Furthermore, in the extreme case, the concentration of chlorine becomeszero, and water without the bactericidal activity may be drunk. Theconcentration decrease of residual chlorine causes the degradation ofthe bactericidal activity of water, which may cause the breeding ofmicrobes, and especially of pathogenic microbes (for example, 0-157coliform bacilli), and further cause a social problem concerning thesafety and health of people. On the other hand, increasing theconcentration of chlorine in drinking water to a higher level tomaintain the bactericidal activity of drinking water causes the problemof a bleaching powder smell or a safety problem of producing harmfulsubstances such as a chloric residuum of trihalomethane.

As to the chromaticity and the turbidity of drinking water in the endside pipes also, problems similar to the above-mentioned problems arecaused due to the long staying time of water. In particular, a waterstorage tank is used in aggregate residences or business establishments,and if the water storage tank is not well managed, the above problemsare often caused.

In an ideal water quality management system, the quality of water in theend side pipes, which end users drink, is monitored, and is adequatelymanaged based on the results of the monitoring. The size of aconventional water quality meter, for example, 1.2 m×1.8 m×0.6 m, is solarge that it cannot be provided in places such as a typical house oraggregate residences. Since the price of a conventional water qualitymeter or the cost of providing a conventional water quality meter ishigh, the number of conventional water quality meter provided in typicalhouses or aggregate residences is small. Furthermore, since professionalexpertise is required for the maintenance of a conventional waterquality meter and the consideration for the safety of a meter isimportant, it is difficult to use a conventional water quality meter intypical houses. Thus, conventional water quality meters have not beenprovided at a desirable pipe location in the neighborhoods of houses ofend users or of aggregate residences.

On the other hand, although the quality of water at the end side of awater distribution piping network can be measured by a manual analysisor with a portable water quality meter, it takes a long time formeasuring results to be obtained, and water quality data cannot becontinuously obtained, which makes it impossible to determine the rangeof variation in water quality in a day, or the transient behavior ofwater quality.

In water quality data, the maximum and minimum values in a transientstate are important, and the development of a system and a controlmethod of the system to reduce the variation in these values ismandatory. Therefore, a manual analysis or a portable water qualitymeter is not suitable for the above continuous monitoring system.

In a very rare example, by restricting measurement categories and placesin which water quality detectors are provided, for example, by providingresidual chlorine concentration detectors at the rate of one per ten tothirty-plus thousand end users at end side pipes of a water distributionsystem, an on-line water quality measurement has been performed.However, conventional water quality meters used in the above waterquality measurement can measure only one category, and are also largeand expensive meters similar to ones used in water purifying facilities.Therefore, places in which such meters are set cannot be easilyobtained, and it is also to difficult to obtain sufficiently detailedmeasurements of water quality.

SUMMARY OF THE INVENTION

The present invention has been achieved in consideration of the abovedescribed problems, and is aimed at providing a water quality meter anda water quality monitoring system in which water quality meters can beset at places near the end side pipes of a drinking water distributionsystem, and further can measures a plurality of measurement categories.

To attain the above object, the present invention provides a waterquality meter attached at a location on a pipe in a water distributionsystem which supplies water that is obtained by purifying raw water asdrinking water to each end user via a water distribution piping network,the water quality meter comprises:

at least one analyzing unit for analyzing a water sample introduced fromthe location on the pipe; and

a liquid introducing unit composed of a single member in which aplurality of fluid flow paths for feeding various types of liquidincluding the water sample into the analyzing unit are formed.

Moreover, in the above water quality meter, the member composing theliquid introducing unit is made of plastic which is cured by ultravioletirradiation.

Further, in the above water quality meter, the analyzing unit includes ameasurement flow path in which liquid flows, and a plurality ofapertures open to the measurement flow path, with liquid to be fed intothe analyzing unit from the liquid introducing unit being introduced tothe measurement flow path through the apertures.

Furthermore, the above water quality meter further includes a pluralityof containers for liquid to be fed into the analyzing unit, the liquidin the containers being fed into the analyzing unit via the fluid flowpaths in the liquid introducing unit.

Still further, in the above water quality meter, liquid stored in eachof the containers is one of a reagent prepared corresponding to ameasurement category, washing water to wash the measurement flow path,and reference water to be used for correcting a result of a measurementperformed by the analyzing unit.

Also, in the above water quality meter, the containers are detachablyattached to the water quality meter.

Additionally, in the above water quality meter, the analyzing unit isfabricated by using a micro-fabrication technique.

On top of that, in the above water quality meter, a plurality ofanalyzing units is connected to the liquid introducing unit.

Moreover, in the above water quality meter, a plurality of analyzingunits analyzes the same measurement category.

Also, the present invention provides a water quality monitoring systemfor monitoring the quality of water distributed by a water distributionsystem including water purifying facilities to purify raw water taken infrom rivers, lakes, and/or wells to a quality suitable for drinkingwater, water distribution facilities for distributing the water purifiedby the water purifying facilities, a water quality control center formonitoring and controlling the water purifying facilities and the waterdistribution facilities, and a water distribution piping network forfeeding the purified water to end users, the water quality monitoringsystem comprises:

water quality monitoring meters set at predetermined locations in thewater distribution piping network, each of the water quality monitoringmeters including at least one analyzing unit for analyzing a watersample introduced from the location on the pipe; a liquid introducingunit composed of a single member in which a plurality of fluid flowpaths for feeding various types of liquid including the water sampleinto the analyzing unit are formed; and a transmission unit fortransmitting to the control center;

wherein results of measurements performed by each of the water qualitymeters are transmitted to the water quality control center via thetransmission unit of the water quality meter.

Further, in the above water quality monitoring system, each of the waterquality meters is set in one of a manhole, a fire hydrant, a water meterbox, a utility in the house of an end user, all of which are provided inthe water distribution network.

Still further, in the above water quality monitoring system, thetransmission between the control center and each of the water qualitymeters is performed with a radio transmission.

Furthermore, in the above water quality monitoring system, each of thewater quality meter includes a solar battery and a storage batteryconnected to the solar battery via a diode, and the water quality meteris powered by energy fed from the solar battery and/or the storagebattery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the composition of a water qualitymeter of an embodiment according to the present invention.

FIG. 2 shows an example of the composition of a drinking waterdistribution system using a water quality monitoring system with waterquality meters of the embodiment according to the present invention.

FIG. 3 shows an example of a method of setting a water quality meter atan end user side in a water quality monitoring system of an embodimentaccording to the present invention.

FIG. 4 is a schematic block diagram showing the internal composition ofa water quality meter of the embodiment according to the presentinvention.

FIG. 5 shows the detailed structure of a mother board used in theembodiment according to the present invention.

FIG. 6 is a perspective view showing a three-dimensional structure offluid flow paths used in the mother board.

FIG. 7 is a vertical cross section showing the composition of a mixingand analyzing unit in a water quality meter of the embodiment accordingto the present invention.

FIG. 8 shows the composition of an analyzing cell in each mixing andanalyzing unit.

FIG. 9 shows another example of a method of setting a water qualitymeter at an end user side in the water quality monitoring system of theembodiment according to the present invention.

FIG. 10 shows an example of a water quality monitoring system of anotherembodiment according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereafter, details of the embodiments will be explained with referenceto the drawings. FIG. 2 shows an example of a basic composition of adrinking water distribution system using a water quality monitoringsystem with water quality meters of the embodiment according to thepresent invention. Raw water taken from rivers, lakes, wells, and so onis purified to make the water quality suitable for drinking water by thewater purifying facilities 1, and is sent to the water distributionfacilities 2. The drinking water output from the water distributionfacilities 2 is introduced into a water quality meter 8 via a waterdistribution system main pipe 4 and a water distribution subsystem mainpipe 5, or further via a water supplier sub-pipe 6 and an end-user sidepipe 7. Each water quality meter includes a transmission means, and canperform the transmission with a water quality control center 3.Information on the quality of the distributed drinking water which hasbeen measured in an on-line manner by the water quality meters 8 istransmitted to the water quality control center 3 by a radio means, aline transmission method, a transmission satellite, etc. The waterquality control center 3 then processes the received information, andcontrols the water purifying facilities 1 and the water distributionfacilities 2 so as to ensure that the quality of distributed water is ina state suitable for drinking water.

FIG. 3 shows an example of a method of setting a water quality meter atan end user side in a water quality monitoring system of an embodimentaccording to the present invention. The distributed drinking waterbranched from the water distribution subsystem main pipe 5 on the watersupplier side, the water supplier side sub-pipe 6, or the end-user sidepipe 7, enters the end-user piping 11 via a shut off valve 10 and awater meter 9, and a plurality of measurement categories for the qualityof the drinking water is simultaneously measured by the water qualitymeter 8. The end-user piping is a network system composed of pipes, andsome of the drinking water is fed to an end user from a location on theend user piping 11 via a feed water faucet 12 such as a water tapfaucet. The water quality meter 8 can be attached before or after thewater meter 9, or in a water meter container box, and further has a sizesuch that it can be easily set in a manhole, a fire hydrant, a utilityin the house of an end user, or in the vicinity of a water tap faucet.Although the composition of the water quality meter 8 is later explainedin detail, in accordance with the embodiment of the present invention,the water quality meter 8 can be easily set in a space of 10 cm×20 cm×20cm.

FIG. 4 is a schematic block diagram showing the internal composition ofa water quality meter of the embodiment. Water sample introduced fromthe pipes 4, 5, 6, and 7 via a liquid introducing unit 13 is measuredfor each measurement category by the mixing and analyzing unit 110,using a predetermined measuring sequence, and the measured value for thecategory is converted to an electrical signal. Further, the electricalsignal is sent to a signal processing/control unit 18. The mixing andanalyzing unit 110 is composed of a plurality of reagent mixing parts 14a- 14 c provided for the respective measurement categories, and aplurality of measuring parts 15-17 corresponding to the respectivereagent mixing parts 14 a- 14 c. Each of the plurality of reagent mixingparts 14 a- 14 c and the plurality of measuring parts 15-17 is formed asa cell with a module structure. Therefore, it is easy to provide cellscorresponding to the number of required measurement categories. Themeasurement categories are the concentration of residual chlorine, theturbidity, the chromaticity, the conductivity, pH, the concentration ofchloric residua such as trihalomethane, the number density of pathogenicmicrobes, and so forth. The signal processing/control unit 18 receivespower from a power source unit 20, and processes result data ofmeasurements performed by the mixing and analyzing unit 110. The resultdata processed by the signal processing/control unit 18 are converted tosignals for transmission by a transmission unit 19. Further, theconverted signals for transmission are transmitted to the water qualitycontrol center 3 by a radio means, or a telemeter via an exclusivetransmission line or a public transmission line.

By applying a micro-fabrication technique, the mixing and analyzing unit110 can be fabricated in a very small size, and the power consumptionand the amount of the water sample and mixed reagent can be reduced.Accordingly, a battery can be used as the power source unit 20, andwithdrawal collection or evaporation of the exhaust water becomespossible, which makes constructing work for equipment to process theexhaust water from the water quality meter 8 unnecessary. In addition,wiring works for data transmission from the water quality meter 8 alsobecome unnecessary because a radio data transmission line is used. Thus,the freedom of choice in locating the water quality meter 8 is greatlyexpanded.

In the following, the detailed composition of a water quality meter ofthe embodiment will be explained with reference to FIG. 1. The waterquality meter 8 is constructed by attaching pumps (74, 84, 87, and 90),electromagnetic valves (69, 73, 83, 93, 75 a- 75 c, 85 a- 85 c, and 91a- 91 c), and analyzing cells (76, 77, and 78), to a mother board 101.Here, diaphragm valves and metering pumps (syringe pumps) are used forthe pumps 87 and 89 and the pumps 74 and 84, respectively. Moreover,fluid flow paths are formed in the regions surrounded by dotted linesshown in FIG. 1, inside the mother board 101. Drinking water 52 flowingin a pipe 51 at the water supplier or end user side is sampled via apipe 53. Further, the sampled drinking water passes through a manualvalve 54, a pipe 55, a depressurization valve 56, a pipe 57, a manualvalve 58, and is sent to an exhaustion conduit 60 from a pipe 59.

A part of the water sample 52 whose pressure is maintained at a constantvalue is branched from the pipe 57 by the pipe 61, and is introduced toa filter 63 for removing comparatively large extraneous substances inthe branched water via a manual valve 62. Further, the water isintroduced to a degassing tank 66 via a flow path 65 in the mother board101. Inside the degassing tank 66, bubbles contained in the water sample52 gather in the upper part of the degassing tank 66, and this gas isexhausted at appropriate intervals to the exhaust water conduit 60 fromthe mother board 101 via an electrode 69 and a flow path 70.

Water sample 71 in the tank 66, from which bubbles are removed, isintroduced to the metering pump 74 via a flow path 73 and theelectromagnetic valve 73. Moreover, the water sample 71 is selectivelysent to the plurality of analyzing cells 76, 77, and 78, each analyzingcell analyzing an independent measurement category, via the plurality ofelectromagnetic valves 75 a, 75 b, and 75 c, and a plurality of fluidinlet holes 71 a, 71 b, and 71 c. The shape and size of the analyzingcells 76-78 are the same, and the arrangement of the flow paths in thecells is also the same, so that the cells interchangeable with eachother. Also, these analyzing cells are detachably held on the upper faceof the mother board 101. Furthermore, a plurality of cartridges 79, 80,and 81 containing liquid are held detachably held on the outside of themother board 101, and liquid contained in each cartridge is fed to themother board 101. Liquid 82 (reagent) from the cartridge 79 isselectively sent to the analyzing cells 76-78, the electromagnetic valve83 and the metering pump 84, via one of the plurality of electromagneticvalves 85 a- 85 c that corresponds to the selected analyzing cell, andalso via one of the plurality of flow inlet holes 82 a- 82 c thatcorresponds to the selected analyzing cell.

Similarly, liquid 86 (washing water) from the cartridge 80 isselectively sent to the analyzing cells 76-78 by the metering pump 87,via one of the plurality of electromagnetic valves 88 a- 88 c thatcorresponds to the selected analyzing cell, and also via one of theplurality of flow inlet holes 86 a- 86 c that corresponds to theselected analyzing cell. Also, liquid 89 (reference water) from thecartridge 81 is selectively sent to the analyzing cells 76-78 by themetering pump 90, via one of the plurality of electromagnetic valves 91a- 91 c that corresponds to the selected analyzing cell, and also viaone of the plurality of flow inlet holes 89 a- 89 c that corresponds tothe selected analyzing cell.

Each analyzing cell (whose structure is later explained in detail) iscomposed of a reagent mixing part in which mixing or a reaction of thewater sample with the liquid fed from each cartridge is performed; orliquid fed from each cartridge flows through along with a measuring partfor measuring liquid sent from the reagent mixing part for apredetermined measurement category, and is shaped by a micro-fabricationtechnique. Thus, although the size of this analyzing cell is very small,its function is equivalent to that which one set of analyzing equipmentof a conventional size possesses. Last, exhaust water 92 whose analysishas been finished is expelled to the outside of the water quality meter8 via flow paths 70. If the exhaust water 92 is harmful, or there is nota water exhaust utility, the exhaust water 92 is expelled into anexhaust water storage container 95.

Furthermore, in the following, details of the mixing and analyzing unit110 will be explained with reference to FIG. 5. The shape of the motherboard 110 is a rectangular parallelepiped, and there are connectionholes for inputting and outputting water sample on the right side faceof the mother board 110 with the electromagnetic valves 93 and 69 beingattached to the corresponding holes. Moreover, the flow inlet holes 89a- 89 c and 82 a- 82 c for inputting the reference water 89 and thereagent 82 are arranged longitudinally, and the electromagnetic valves88 a- 88 c and 91 a- 91 c are attached to the corresponding holes. Onboth sides of each of the longitudinally arranged inlet holes, there isa pair of internal threads, and each of the electromagnetic valves 93,69, 88 a- 88 c, and 91 a- 91 c, is fixed to the mother board 101 withscrews by using the internal threads.

Similarly, there are flow inlet holes for inputting water sample on theleft side face of the mother board 101, and the electromagnetic valves83 and 73 are attached to the corresponding holes. Moreover, the flowinlet holes 71 a- 71 c for inputting water sample and 86 a- 86 c forinputting the washing water 86 are arranged longitudinally, and theelectromagnetic valves 75 a- 75 c and 85 a- 85 c are attached to thecorresponding holes. Also, on both sides of each of the longitudinallyarranged inlet holes, there is a pair of internal threads, and each ofthe electromagnetic valves 83, 73, 85 a- 85 c, and 75 a- 75 c, is fixedto the mother board 101 with screws by using the internal threads.

On the other hand, on the upper face of the mother board 101, there areopen holes are formed to communicate with the pumps 74, 84, and 87, sothat pressure is applied to fluid flowing in the mother board 101 so asto send the fluid onward. Furthermore, the analyzing cells 76-78 arefixed to the upper face. These analyzing cells 76-78 are connected tothe mother board 101 via the flow inlet holes 82 a- 82 c, 71 a- 71 c, 89a- 89 c, 86 a- 86 c, and 309 a- 309 c.

The main fluid flow paths formed in the mother board 101 are explainedbelow with reference to FIG. 6. All the internal fluid flow paths (paths65, 68, 70, 72, 92, 94, etc.) are three-dimensionally formed in themother board 101.

On the back face of the mother board 101, there are flow inlet holes forintroducing the water sample 52, the reagent 82, the washing water 86,and the reference water 89. As mentioned above, the shape of the motherboard 101 is a rectangular parallelepiped, and on its outer surface,there are a plurality of flow inlet or connection holes and a pluralityof internal threads for holding valves, pumps, analyzing cells, etc. viasealing elements without connection pipes on the surface of the motherboard 101.

If the resin parts are removed from an illustration of the mother board101, and only the internal fluid flow paths are illustrated, the pathsare seen as shown in FIG. 6. Such three-dimensional fluid flow pathshave rarely been realized. If one intends to form such stereoscopicfluid flow paths, the paths should be conventionally formed bysuperimposing a plurality of plates in which two-dimensional paths aremechanically formed. This embodiment adopts a photo-forming method inwhich a three-dimensional shape is formed by irradiating a part of theshape in liquid ultraviolet-curing type plastic in a transparentcontainer with an ultraviolet laser beam. To form the three-dimensionalfluid flow paths in this embodiment, parts of the three-dimensionalfluid flow paths in ultraviolet-curing-type plastic are not irradiatedwith an ultraviolet laser beam, and these parts remain as liquidplastic. Afterward, by washing out the liquid plastic which has notcured, the remaining solidified plastic parts complementary to thethree-dimensional fluid flow paths can be obtained. In this embodiment,transparent ultraviolet-curing-type epoxy resin is used so that statesinside the fluid flow paths can be observed. The photo-forming methodcan cheaply and quickly form a three-dimensional shape using onlythree-dimensional data of the shape (which are used for CAD), without ashaping mold which and further improves the reliability of theconnection parts of the fluid flow paths and the external equipment suchas valves, pumps, and so on.

As shown in FIG. 6, the sizes or shapes of the fluid flow paths in themother board 101 can be freely designed while satisfying a constraint inthat two points are connected with the shortest three-dimensionallysmooth-curve route without steep bending, which causes very littlestagnation of dust and bubbles in fluid in the fluid flow paths.

Furthermore, since a branch or a connection in the flow paths can beformed at an optional position inside of the mother board 101 without acoupling element, mixing or separating of fluid can be performed at anoptional position inside of the mother board 101. The degassing tank 66can also be formed in a space with the three-dimensional shape of adegassing tank 104 shown in FIG. 6.

In the above monitoring system according to the present invention, theplurality of pumps and electromagnetic valves are controlled by asequence control method, and drinking water 52 sampled from the drinkingwater distribution pipe 51 and liquid in each of the plurality ofcartridges are introduced into the corresponding reagent mixing part.Further, In the reagent mixing part, the introduced liquid reacts withthe water sample, and the result of the reaction is measured by themeasuring part. Here, In cases where a reagent is not used, no reagentis introduced.

In a typical case according to the embodiment, the water sample isdrinking water distributed by a water distribution system and a reagentsuch as DPD or orthotolidine reacting with chlorine and causing colordevelopment. Moreover, washing water such as dilute chloric acid,neutral detergent, etc.; and reference water such as pure water,calibration water, etc. are selected as liquid 86 in the cartridge 80and liquid 89 in the cartridge 81, respectively. The water sample, thereagent, the washing water, and the reference water are introduced tothe corresponding analyzing cells at a predetermined interval using asequence control method. In the above case, the analyzing cells 76, 77,and 78 are used as a residual chlorine concentration meter, achromaticity meter, and a turbidity meter, respectively. The reagentliquid 82 is introduced only to the analyzing cell 76 allocated as theresidual chlorine concentration meter.

Naturally, a measurement category can be changed by changing the type ofreagent, and the allocation of each analyzing cell to some one of therequired measurement categories is optional.

In the residual chlorine concentration meter, the degree of colordevelopment due to the reaction of the water sample and the reagent ismeasured by an absorptiometric method. In the chromaticity meter, areagent is not used, and the absorbance of water sample is measured.However, since the absorbance of the water sample is low, a comparisonmeasurement method is adopted using the reference water (pure water),and a base level of the zero absorbance is calibrated for apredetermined period. As for the turbidity meter, neither reagent norreference water is used, but impurity particles are counted. Further,the total number is converted to the turbidity value.

Moreover, if an analyzing cell with electrodes is used, the conductivityor pH of the water sample can be measured without changing the structureof the analyzing cell.

A predetermined quantity of the washing water liquid 86 is introduced toeach analyzing cell at prescribed time intervals, and washes the fluidflow paths in the analyzing cell, the electrodes, and so on. Substanceswashed out from the analyzing cells are expelled from the mixing andanalyzing unit 110 along with the water sample 71 or the reference water89.

Here, although one cartridge is used for the reagent in this embodiment,a plurality of cartridges can be provided for reagents, and varioustypes of reagent can be used for the different measurement categoriesfor which a reagent is necessary, by using a selection valve, forexample.

In the following, details of the structure of each of the analyzingcells 76, 77, and 78 shown in FIG. 4 will be explained with reference toFIG. 7 and FIG. 8. Although only the analyzing cell 76 is explainedbelow, the structure of the other cells 77 and 78 are the same as thatof the cell 76, and explanations for the structures of the cells 77 and78 have therefore been omitted.

Although the principle of measurement performed in each analyzing cellis different from those of the other analyzing cell (the absorptiometryfor a predetermined wavelength is carried out in the residual chlorineconcentration meter and the chromaticity meter, and a fine particlenumber coefficient method is adopted for the turbidity meter. Moreover,the conductivity or pH can be measured by using an analyzing cell withelectrodes.), the analyzing cells have a module composition in whichboth the size and shape, and the arrangement of the internal fluid flowpaths, are common among the analyzing cells. Although the threeanalyzing cells are detachably attached to the upper surface of themother board 101 in this embodiment, the number of analyzing cells isnot restricted to three. That is, by changing the arrangement of theinternal fluid flow paths in the analyzing cells, the number ofanalyzing cells mounted on the mother board 101 can be freely changed.Also, the arrangement of the analyzing cells is arbitrary. By selectinga liquid or a reagent for an analyzing cell according to a measurementcategory, and setting a measurement sequence, it is possible to set theanalyzing cell to perform a required measurement function.

In another example, all of the analyzing cells can be set so as tomeasure the same measurement category. By setting a plurality ofanalyzing cells measuring the same measurement category on the motherboard 101, the reliability of the measurement for that category can beimproved. Accordingly, even if a malfunction occurs in one of theanalyzing cells, the measurement can be continued by using the remainingnormal cells, which can extend the life time of the total monitoringsystem.

As shown in FIG. 7, each analyzing cell is composed of the reagentmixing part 201 (flow cell substrate 325) and the measuring part 202(measurement cell substrate 209). The structure of the reagent mixingpart (flow cell substrate 325) is explained in detail below withreference to FIG. 8. The flow cell substrate 325 has a duplex layeredstructure of a silicon substrate 301 and a Pyrex glass cover 302, and isfabricated by the micro-fabrication technique. An S-shaped fluid flowpath 305, an inclined face 303 and a flat bottom face 304 are formed inthe substrate 301 by shaping a wafer of highly pure silicone using ananisotropic etching. Furthermore, a plurality of rectangular penetratingholes 306, 307, 308, and 309, and a mesh-type hole 310 in which fineholes with a diameter of several micrometers are formed in a mesh statewith a pitch of 100-200, μm, are also on the back side of the substrate301. All of the holes 306-310 are connected to the fluid flow path 305.Moreover, the cover 302 is connected to the upper surface of thesubstrate 301 by an anodic bonding method. The substrate 301 and thecover 302 are connected to each other to which a predetermined voltageis applied at a high temperature in a vacuum state in a wafer size.Afterward, the wafer is cut to as a required size for use. The usagesize, which depends on the shape of the flow path 305, is about 1 cm×2cm.

One of the various types of liquid (water sample 71, reagent 82, washingwater 86, and reference water 89) is selected and fed to each agentmixing part 201 (flow cell substrate 325), by selectively driving theelectromagnetic valves and the pumps attached to the side faces of themother board 101. In this embodiment, the reference water 89, thewashing water 86, water sample 71, and the reagent 82 are fed to theholes 306, 307, 308, and 310, respectively. The liquid flows in the flowpath 305, is introduced to the straight path 311, and finally expelledto the outside of the analyzing cell.

Here, in this embodiment, the liquids from the cartridges are injectedto the penetrating holes so that at the further upstream the position inthe fluid flow path, the cleaner (purer) the water that flows. By theabove liquid injection method, the whole of the flowpath 305 can becleaned. In addition, by filling the flow path 305 with the cleanestwater, for example, the reference (pure) water, when measurements arenot being made, and introducing the other liquid only for measurements,the degradation of measurement sensitivity due to the contamination ofthe flow paths 305 can be prevented.

Furthermore, all of the various types of liquid flow in different pathseach in the mother board 101. That is, the various types of liquid areseparately fed to the flow cell substrate 325, and never mixed until theliquid enters the flow path 305 in which a measurement such as theabsorbance measurement is executed. Therefore, since the mixing of thevarious types of liquid occurs just before the measurement, thecontamination of the flow paths in the mother board 101 due to themixing of the various types of liquid is kept as low as possible, whichcan result in highly accurate measurements.

Next, the measuring part 202 (measurement cell substrate 209) will beexplained. A light emitting element 203 such as an LED, a laser diode,etc., a lens system for converging a light beam emitted from the lightemitting element 203 at the inclined face 303 in the straight path 311,and a light detecting element 205 for monitoring changes in the quantityof the light beam are arranged in the measurement part 202. Theconverged light beam 206 which has been transmitted through the straightpath 311 is reflected by the inclined face 303′ opposite to the inclinedface 303, and returns to the measurement part 202. The light beam whichhas returned to the measurement part 202 is measured by a lightdetecting element 208 provided in the measurement part 202. The lightemitting element 203, the light detecting elements 205 and 208, the lenssystem 204, and the straight path 311 are attached to the measurementcell substrate 209 so that their relative positions are fixed. Further,the measurement cell substrate 209 is detachably attached to the motherboard 101.

Although explanations for the other analyzing cells for the chromaticityand the turbidity are omitted, for these cells, the shape and size ofthe analyzing cells 76-78 are common, as is the arrangement of flowpaths.

The residual chlorine concentration meter for which the analyzing cell76 is used is explained below. In this residual chlorine concentrationmeter, while the washing water 86 and the reference water 89 are notfed, the water sample 71 and the reagent 82 are fed to the concentrationmeter at a predetermined ratio, and mixed in the flow path 305. Here,the reagent 82 is injected into the water sample through the mesh-typehole 310. By passing the reagent 82 through the mesh-type hole 310, thereagent 82 can be homogeneously injected into the water sample, whichwill enable the reagent 82 to diffuse in the water sample for a shorttime. Accordingly, the color development reaction of the water sample 71and the reagent 82 is quickly completed with the degree of colordevelopment being proportional to the residual chlorine concentration.The mixture of the water sample 71 and the reagent 82 in which the colordevelopment reaction has been completed is introduced to the straightpath 311, and the degree of color development is measured by theabsorptiometric method. While measuring the absorbance of the mixture,the flow of the mixture is temporarily stopped so as to stabilize themeasured value. After the measurement, the measured mixture 312 isexpelled through the penetrating hole 309. When calibrating thesensitivity for or the zero point of the degree of color developmentproportional to the residual chlorine concentration, the reference water89 whose chlorine concentration was measured in advance is fed into theanalyzing cell 76, and the degree of color development is measured usingthe above-explained procedures. This measured value for the degree ofcolor development is used as the reference value to correct the measuredvalues for the degree of development. The washing water 86 is fed intoeach analyzing cell to wash and remove mineral or plant contaminants inits reagent mixing part (especially in the straight path 311)corresponding to the grade of contamination.

Here, in the structure of the analyzing cell according to the presentinvention, if fine extraneous substances or bubbles adhere to the insideof the flow path 311, the quantity of the light beam 206 transmittingthrough the path 311 changes considerably, which makes it impossible tocorrectly measure the absorbance of the mixed liquid. Since the fineextraneous substances or bubbles are very small, and adhere to manydifferent locations, all of the extraneous substances or bubbles cannotremoved by the usual procedure of washing the flow paths in eachanalyzing cell. In the present invention, a plurality of washing liquidfeeding patterns other than the usual washing liquid feeding procedureis prepared, and any one of the patterns can be selected.

The prepared washing liquid feeding patterns are as follows.

(1) The water sample 71 is fed as the washing liquid. That is, since thepump 74 for feeding the water sample 71 is a metering pump, this pumpcan feed the washing liquid using high pressure although the flow rateof the washing liquid has a definite value. The fine extraneoussubstances and bubbles are removed by the water sample 71, which is fedat a higher pressure than a water sample fed for a usual measurement.

(2) The washing water 87 and/or the reference water 81 is fed as thewashing liquid. That is, since the pumps for feeding the washing water87 and the reference water 81 are diaphragm pumps, and feed liquid witha pulsating flow, the fine extraneous substances and bubbles are removedby the pulsating flow.

(3) The washing water 86 (which is more effective if it includessurfactant) is fed to the straight path 311, and remains there for atime. Afterward, the path 311 is washed by the water sample 71. Thispattern is effective for contaminant which cannot be removed by a changein the flow rate, as in pattern (2).

In accordance with the present invention, the fine extraneous substancesand bubbles can be removed by using one or a combination of the abovewashing liquid feeding patterns, which can provide a more reliable waterquality meter. Moreover, the washing liquid feeding pattern can bedesignated from the water quality control center 3 by a remotetransmission.

In FIG. 9, another water quality monitoring system of a compositiondifferent from that of the system shown in FIG. 3 is shown. In theembodiment shown in FIG. 9, the water meter 9 and the water qualitymeter are integrated. Since the water quality meter according to thepresent invention can, by adopting the micro-fabrication technique, bemade smaller while retaining the ability of to measure a plurality ofmeasurement categories, the water quality meter can be incorporated intothe water meter 9. The water distributed to each end user flows throughthe water meter 9 via the water supplier side sub-pipe 6 and the shutoff valve 10, and the flow rate of the water is measured by the meter 9.Simultaneously, part of the water is fed into the water quality meter 8via a water sample-introducing pipe 24. According to this composition,the integrated water meter and water quality meter are contained in thebox for the water meter 9, and can be attached to a water distributionpipe for the end user. Thus, a special space and/or an specialattachment labor for the water quality meter become unnecessary, and theintegrated water meter and water quality meter can be as easily attachedas a conventional water meter.

In FIG. 10, another water quality monitoring system of a compositiondifferent from that of the system shown in FIG. 9 is shown. In theembodiment shown in FIG. 10, power fed to the water quality meter isgenerated in the system itself with solar batteries. The power generatedby the solar batteries is fed to the water quality meter via a diode 22,and surplus power is stored in a storage battery 23. If the sunlightenergy is not obtained at night or on a rainy day, the storage battery23 backs up power supplied to the water quality meter by discharging thestored energy. The diode 22 is provided as a protection means forpreventing a reverse current flow to the solar batteries 21 whendischarging energy from the storage battery 23. According to the abovecomposition, by selecting the proper capacity for the solar batteries 21and that for the storage, battery 23, an autonomous operation of thewater quality meter without external power becomes possible. Equipmentor labor to secure AC power is not necessary, which can remove thelimitation for selecting the location of the water quality meter andreduce the cost of fabrication.

Since the above-explained water quality meter 8 is located at the houseof each end user, the control center 3 can control the quality of waterdistributed to each end user. In another example, the water qualitymeters are located at houses at a ratio of one to thirty-plus houses,which can reduce the quantity of transmitted data between the controlcenter 3 and the water quality meters to one thirtieth or less of theoriginal volume, and greatly reduce the load of data processing in thecontrol center 3. Furthermore, it becomes possible to control thequality of water distributed to end users with the remarkably higheraccuracy than a conventional system which can control the quality ofwater at the end user side only at a ratio of one to several hundreds ofthousands of houses.

Furthermore, since the size of the water quality meter 8 according tothe present invention has been considerably decreased with themicro-fabrication technique, the quantity of the water sample or reagentused for the water quality measurements can be reduced to a level ofmicro-litters. Accordingly, the time interval for refills of thereagent, washing water, etc. can be extended by more one month even withcontinuous measurements.

The above embodiments are summarized as follows.

(1) The water quality meter according to the present invention is set atthe end side part of the water distribution piping network, near or inthe house of each end user, and a control center performs collectivewater quality control based on information transmitted from each waterquality meter.

(2) The water quality meter is set in a manhole, a fire hydrant, a watermeter box, a utility (for example, under a drain in the house of an enduser), etc. Thus, the possibility that ordinary people might touch thewater quality meter is decreased, and so the safety can be assured.

(3) The sample inlet unit, the reagent mixing part, and the measuringpart, which generally increase the size of a measurement apparatus, aremade much smaller by adopting the micro-fabrication technique. The sizeof the water quality meter can be decreased to one-thousandth of that ofa conventional water quality meter by using the presently developedmicro-fabrication technique.

(4) The three-dimensional fluid flow paths in the analyzing cell areformed by using ultraviolet-curing-type plastic, which can make possiblea tubeless structure. Thus, the mixing and analyzing unit can be madesmaller, and the reliability of the unit can also be improved.

(5) The fabrication and an installation cost of the water quality meterare decreased by making the meter smaller, and since themicro-fabrication technique is used in the silicon semiconductor elementprocessing, the fabrication cost can be greatly decreased even furtherby mass-producing water quality meters according to the presentinvention.

(6) The quantity of liquid used for the water quality measurement can bereduced to a level of micro-litters because the size of the waterquality meter is very small. Thus, the period for refills of the reagentcan be extended by more one month even if the measurements arecontinuously performed. Moreover, the quantity of exhaust water is verysmall, and if an exhaust water withdrawal and collection, or evaporationmethod is adopted, the installation of exhaust water equipment is notnecessary.

(7) The reagent, the reference water, and so on, which are consumed inthe measurements, are each stored in cartridges and fed to the analyzingcells each, which can make refilling them very easy.

(8) The decrease in size of the water quality meter also greatlydecreases its power consumption. Thus, a built-in battery or a solarbattery can be used as a power source, and transmission wiring alsobecomes unnecessary by using a radio circuit as a signal transmissionmeans.

(9) The composition of the fluid flow paths is such that the varioustypes of liquid to be used are not mixed before reaching each analyzingcell, which can prevent contamination in the flow paths. Furthermore, aplurality of penetration holes for introducing various types of liquideach are formed in a flow path in each analyzing cell, and these varioustypes of liquid are introduced from the respective penetration holes sothat the further upstream the position in the fluid flow path, thecleaner the liquid (the purer the water) that flows, which can suppresscontamination in the flow path in the analyzing cell.

(10) Since it is assumed that fine extraneous substances or bubbles willadhere to the inside surface of the flow path in the analyzing cell if acomparatively large variation occurs in the results of the measurement,one of a variety of prepared washing liquid feeding patterns other thanthe usual washing water feeding procedure is selected and executed toremove the fine extraneous substances or bubbles.

In accordance with the present invention, the effects described belowcan be expected.

(1) Since a water quality meter with a size of one-thousandth of that ofa conventional water quality meter can be provided, the flexibility inthe installation of the meter can improved.

(2) Since a water quality meter of a small size and minimal powerconsumption can be achieved, it is possible to construct an on-linewater quality monitoring system which can measure a plurality ofmeasurement categories without wiring by using a battery as a powersource and a radio transmission means.

(3) By adopting a module structure for the analyzing cells, theselection, combining, or changing of the measurement categories is easy,which enables it to be more flexible in responding to changes in themeasurement sequence.

(4) By applying a photo-forming method using ultraviolet-curing in theformation of three-dimensional fluid flow paths with three-dimensionalCAD data of the flow paths, the three-dimensional fluid flow paths canbe formed without using a mold, by which the water quality meter can becheaply and quickly fabricated.

(5) Since a micro-sized sampling and analyzing unit can be fabricated,the quantity of liquid needed for the water quality measurement isreduced, which can considerably extend the time interval for refills ofthe liquid.

(6) Since various types of liquid to be used for the measurement are notmixed until just before the measurement is performed, the contaminationof the internal fluid flow paths can be prevented, which can greatlyimprove the accuracy of the water quality measurement.

As explained above, in accordance with the present invention, it ispossible to provide a micro-sized water quality meter with a highreliability, and a water quality monitoring system using the waterquality meter.

Speaking in greater detail, since a water quality meter has a size ofone-thousandth of that of a conventional water quality meter can beprovided, it is possible to provide a water quality meter of a verysmall size and a low water sample flow rate. Accordingly, the waterquality meter can be driven by an internal battery, and continuousmeasurements over a long period are possible with a only small quantityof reagent. Therefore, special wiring and piping are not necessary toinstall the water quality meter, which can greatly reduce theinstallation cost. Thus, the water quality monitoring system can be veryeasily constructed.

Furthermore, since the analyzing cells have a common module structure,it is possible to realize a water quality meter for a variety ofmeasurement categories, in which there is a great deal of freedom in theselection and combination of the measurement categories.

What is claimed is:
 1. A water quality monitoring system for monitoringthe quality of water distributed by a water distribution system thatincludes water purifying facilities to purify raw water taken in fromrivers, lakes, and/or wells to a quality suitable for drinking water,water distribution facilities for distributing the water purified bysaid water purifying facilities, a water quality control center formonitoring and controlling said water purifying facilities and saidwater distribution facilities, and a water distribution piping networkfor feeding the purified water to end users, said water qualitymonitoring system comprising: water quality monitoring meters sized andconfigured for attachment to pipes so as to draw water out of pipesprior to its supply to end users set at predetermined locations in saidwater distribution piping network, each of said water quality monitoringmeters including a plurality of analyzing units each of, which includesa measurement flow path in which liquid flows, for introducing a watersample into said measurement flow path from said location on said pipeand analyzing said water sample; a liquid introducing unit comprising asingle member in which a plurality of fluid flow paths for feeding aplurality of types of liquid including said water sample into saidplurality of analyzing units is formed; and a transmission unit fortransmitting to said control center; wherein results of measurementsperformed by each of said water quality meters are transmitted to saidwater quality control center via said transmission unit of said waterquality meter.
 2. A water quality monitoring system according to claim1, wherein each of said water quality meters is set in a locationselected from the group consisting of a manhole, a fire hydrant, a watermeter box, and a utility in the house of an end user, all of which areprovided in said water distribution network.
 3. A water qualitymonitoring system according to claim 1, further comprising a signalprocessing unit data-processing the measurements results obtained bysaid analyzing unit, said transmission unit converting thedata-processed results obtained by said signal processing unit into atransmitting signal for transmission and transmitting the convertedtransmitting signal to said water quality control center by radio.
 4. Awater quality monitoring system according to claim 1, further comprisinga signal processing unit data-processing the measurement resultsobtained by said analyzing unit, said transmission unit converting thedata-processed results obtained by said signal processing unit into atransmitting signal for transmission and transmitting the convertedtransmitting signal to said water quality control center through anexclusive line or public line.
 5. A water quality monitoring systemaccording to claim 1, wherein each of said water quality meters includesa battery, and each of said water quality meters is powered by saidbattery.
 6. A water quality monitoring system according to claim 1,wherein each of said water quality meters includes a solar battery and astorage battery connected to said solar battery via a diode, and each ofsaid water quality meters is powered by energy fed from said solarbattery and/or said storage battery.